In the early 1990's the Toyota Production System has revolutionised the thinking of manufacturing. Methodologies like Kanban and Single Minute Exchange of Dies are promising cost reductions and productivity increases but so far only a few New Zealand (NZ) companies have successfully implemented some of these methodologies. Further research revealed that not only Toyota's production system but also its whole management system, its product development and its culture contribute to the success of the company being today the largest car manufacturer of the world. Without a doubt, this holistic approach also known as Lean Production coins the current understanding and paradigm within the context of manufacturing and operations. The adaptation and implementation of these Lean principles have successfully found its way into other areas like the health sector and administration processes. However there is still a lack of research regarding manufacture-to-order environments and the adaptation to the requirements of small and medium enterprises (SME). Besides there is hardly any research known, which analyses the influence and role of the national culture during such a Lean transformation. The main objective of the thesis is the development of a Lean transformation framework for manufacture-to-order companies under consideration of their national and organisational context. The focus lies on NZ SMEs that operate in a manufacture-to-order environment characterised by a high degree of variability and by low volumes. In order to assure the practicality of the framework for NZ based industry, the research project followed a case study approach. Five cases are explored. In two of the case studies the researcher was actively involved during the implementation and therefore could verify by iterative interaction with the industry partners the practicality of the developed Lean transformation framework. Data about the leadership profiles, the degree of variability, the level of the integration of Lean methodologies and techniques, the sequence of implementation, and of the actual performance development was collected and analysed by triangulation. For NZ companies who intend to integrate Lean principles and methodologies, the Lean transformation framework can provide valuable guidance on their way to a learning and continuously improving organisation.